For example, a liquid crystal panel for a liquid crystal display device such as a liquid crystal television does not emit light, and thus a backlight unit is required as a separate lighting device. The backlight unit that is provided at a rear side (side opposite to a display surface) of the liquid crystal panel includes: a chassis that is open on a side close to the liquid crystal panel; a light source housed in the chassis; a reflection sheet provided along an inner surface of the chassis and configured to reflect light toward the opening of the chassis; and an optical member (such as a diffuser sheet) provided at the opening of the chassis and configured to efficiently direct the light emitted from the light source to the liquid crystal panel.
For the power saving or the like of the above-configured backlight device, LEDs may be used as the light source. In such a backlight device using the LEDs, a great number of LEDs is arranged, for instance, on a bottom plate of the chassis in a planar arrangement. However, when the light exiting from the backlight unit is observed from the front side, dark regions due to shortage of light amount may be observed at four corners of the screen. As one solution for the above problem, a technique disclosed in Patent Document 1 described below is proposed.    Patent Document 1: Japanese Unexamined Patent Publication No. 2006-120644